Who is responsible for a breach?
You are. That is the short answer, and every firm we verified writes it into their rules.
Your prop-firm agreement binds the account holder, not the software. Apex states it explicitly: results from any trade copier or external program are entirely the account holder's responsibility (Apex PA compliance, verified 2026-08-12). TakeProfitTrader goes further — a violation caused by a copier misconfiguration counts as your own action (Trade Copier Policy). Topstep grants no exceptions for tool malfunctions on API-driven trades. No firm reverses a breach because software did it.
How MirrorFill reduces the risk
Responsibility stays yours; the blast radius does not have to. Each guardrail below is a control you configure, and each has its own article:
- Per-account daily loss limits with Flatten & lock. Set each follower's limit inside its firm's daily loss rule. On breach, the account locks first, then its positions close and its resting orders are cancelled, and it keeps re-sweeping until flat. Daily loss limits and profit targets.
- A leader breach is a per-group kill switch. If the leader account trips its limit, the whole group flattens and stops copying until you resume — followers do not keep mirroring a leader that is already in trouble. Risk locks and the daily reset.
- Max-contract clamps. A follower can never hold more than N contracts, however the leader sizes. One clamp per follower, enforced on every order. Max contracts and blocked instruments.
- Write off, never chase. If a follower order expires unfilled, the missed quantity is written off — never re-sent at market into whatever moved the price. Order expiry and write-offs.
- Restart safety. On restart, positions are read back from the broker, so nothing is copied twice and no phantom position gets "corrected" with a real order. Restarting mid-position.
No false comfort
None of this makes a rule breach impossible, and we will not pretend otherwise. A copier cannot know your firm's rulebook. It cannot fill an order the market will not fill. It cannot act while your connection is down. It cannot stop you from configuring a reverse copy that your firm treats as a hedge. Guardrails shrink the damage a bad minute can do; they do not repeal the rules. Run the pre-flight checklist before the first live trade, and read your firm's row in the policy matrix before that.
Quick answers
My copier malfunctioned and my account breached. Will the firm reverse it?
Almost certainly not. The firms we verified state copier results are the account holder's responsibility, and several add that they give no support and no exceptions for tool failures.
Does using a firm-approved copier shift responsibility to the firm?
No. Approval means the tool is permitted, not that its output is the firm's problem. TakeProfitTrader approves specific copiers and still counts copier-caused violations as yours.
Can MirrorFill enforce my firm's rules automatically?
Parts of them. Daily loss limits, contract clamps, and blocked instruments can encode the numeric rules. Consistency rules, news windows, and hedging bans remain yours to manage.